Device implantable under skin

ABSTRACT

A device implantable under skin is disclosed. The device includes a sealed housing containing electronics for at least stimulation or collection of data and at least one antenna for communicating with an external device, a magnet configured to hold said external device in proximity to the sealed housing. the sealed housing includes an upper cover being closest to the skin when the device is implanted, and a lower cover that is hermetically connected to the upper cover. The lower cover includes an elevated region, a recessed region, and at least one feedthrough element formed in the recessed region of the lower cover.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.14/468,435, filed on Aug. 26, 2014, now U.S. Pat. No. 9,409,018, issuedon Aug. 9, 2016 which claims priority under 35 U.S.C. § 119(a) toApplication No. 13186153.6, filed in Europe on Sep. 26, 2013, all ofwhich are hereby expressly incorporated by reference into the presentapplication.

TECHNICAL FIELD

The technical field relates to small connection ports, known in the artas feedthroughs, which may be used in subcutaneous active medicaldevices. A feedthrough element may include a conductor placed in a smallopening in an electrically insulating material.

BACKGROUND

Many implantable devices use feedthrough elements to connect ahermetically enclosed electronic board to an implanted device such as ameasuring and/or a stimulating electrode and/or an electromechanicalactuator. A feedthrough comprises an electrical connection between ahermetically closed enclosure and the outside surrounded by insulatingmaterial, which allows electrical signals to pass between thesurroundings and the hermetical enclosure while maintaining theintegrity of the hermetic enclosure.

Implantable housings can be made from titanium. In the case of titaniumhousing, feedthroughs for the entire housing unit may be assembled intoone main titanium body. The manufacturing of the titanium body thusrequires a large number of welds, often at least one weld for eachfeedthrough.

Sometimes, each feedthrough is directly brazed onto a titanium body andrequires a complex machined titanium part.

Sometimes the housing is made from alumina (aluminum oxide) which is aceramic. Such a housing may have feedthroughs all around the outerperimeter of the ceramic. One of the technical difficulties with thisdesign is the machining of very small holes (e.g., 0.4 mm diameter) allaround the diameter of ceramic housing, which is made from a very hardmaterial. Another issue is the cost of machining such small and preciseholes, which have to be ground with diamond tools.

SUMMARY

The disclosure describes an implantable device that may be used as acochlear implant that overcomes the challenges noted above, providingease of manufacturing and assembly and also a unique shape of the casingthat facilitates routing of connecting electrodes to the feedthroughelements through a void created between the implanted device and thetissue of a user.

In an embodiment, a device implantable under skin includes a sealedhousing containing electronics for at least stimulation or collection ofdata and at least one antenna for communicating with an external device.The device also includes a magnet configured to hold the external devicein proximity to the sealed housing. The sealed housing includes an uppercover being closest to the skin when the device is implanted and a lowercover that is hermetically connected to the upper cover, the lower coverincluding an elevated region, a recessed region, and at least onefeedthrough element formed in the recessed region of the lower cover.

In an embodiment, the at least one feedthrough element includes a plateshaped base with one or more holes, and the at least one feedthroughelement is configured to connect an electrode, providing electricconnection to the electronics housed within the sealed housing throughconductive pins in the one or more holes.

In an embodiment, the plate shaped base of the at least one feedthroughelement is hermetically joined to the lower cover of the externalhousing.

In an embodiment, the lower cover has a circular disc outer perimetershape, and the lower cover includes an elevated part located radiallyadjacent to the at least one feedthrough element.

In an embodiment, the elevated part is aligned radially with the atleast one feedthrough element, and the elevated part is positionedfarther away from a center of the lower cover.

In an embodiment, the elevated region of the lower cover has a crescentshape spanning more than 50% of the lower cover, the at least onefeedthrough element is surrounded on two sides by ends of the crescentshape.

In an embodiment, the implantable device includes two feedthroughelements, each feedthrough element of the two feedthrough elementshaving a rectangular shape with rounded corners and having 14 connectorpins.

In an embodiment, the implantable device includes two feedthroughelements, each feedthrough element of the two feedthrough elementshaving a circular shape and having 4 connector pins.

In an embodiment, the implantable device includes an electricallyconducting lead connected to the at least one connector pin of thefeedthrough element, and thereby electrically connected to theelectronics in the sealed housing, a silicone overmolding surroundingthe conducting lead, wherein the lead passes through a recessed region,to reach the outer circumference of the lower cover. Here the lead mayconnect or continue to a spirally coiled wire.

In an embodiment, the upper cover has a hollow crown made of abiocompatible material and permeable to electromagnetic waves includingmagnetic fields.

In an embodiment, the hollow crown includes an external wall forming anexternal radial periphery of the sealed housing, and an internal walloriented towards a center of the sealed housing, and the external walland the internal wall form an opening of an annular U-shaped groove.

In an embodiment, the biocompatible material is aluminum oxide. It iswell known that other ceramics such as zirconia toughened alumina, highpurity alumina, or pure zirconia could be used for this purpose butaluminum oxide has been found to be preferable.

In an embodiment, the lower cover is made of titanium. Titanium in thisapplication denotes any titanium alloy or titanium like alloy suitablefor implantation. That is any alloy which may be processed like titaniumand inserted in the body without causing reaction or being degraded.

In an embodiment, the sealed housing is a cochlear implant configured tobe implanted under the skin of a human user and above the user's skullbone.

The disclosure further describes a method of manufacturing animplantable device, whereby a number of manufacturing steps areperformed:

-   -   form a ceramic upper cover with a circumferential flange;    -   form a ceramic feedthrough element with a circumferential flange        and a plurality of feedthrough pins;    -   braze a feedthrough titanium welding flange leak tight onto the        circumferential flange of the ceramic feedthrough element and        braze an upper cover titanium welding flange leak tight onto the        circumferential flange of the ceramic upper cover;    -   form a titanium lower cover by stamping a titanium plate into a        desired shape with a circumference an at least one opening with        an edge;    -   weld the feedthrough titanium welding flange to the edge of the        at least one opening of the titanium lower cover; and    -   weld the titanium lower cover onto the upper cover titanium        welding flange to form a hermetically sealed enclosure with a        plurality of insulated electric connections.        With this method a hermetic sealed enclosure may be made with        very few steps and a high yield is ensured as especially the        feedthrough element may be leak tested prior to the welding        thereof onto the titanium lower cover. The welding between        welding flanges and titanium lower cover may be performed by        laser welding to minimize heat load on nearby elements such as        the feedthrough pins and the electronics within the housing. The        forming of the upper cover may comprise the formation of a        hollow crown including an external wall forming an external        radial periphery of the upper cover, and an internal wall        oriented towards a center of the upper cover, and the external        wall and the internal wall thus forming an opening of an annular        U-shaped groove. In this case, the brazing of an upper cover        titanium welding flange onto the circumferential flange of the        ceramic upper cover comprises both of the brazing of one welding        flange to the internal wall and the brazing of one further        welding flange to an external wall. Also the welding of the        upper cover titanium weld flanges to the titanium lower cover        comprises welding of both internal and external upper cover weld        flanges to the lower cover.

In an embodiment of the method, forming the titanium lower covercomprises stamping elevated parts and regions and providing a recessedregion relative thereto and generating the at least one opening in arecessed region. As the elevated parts and regions are intended to abutthe skull of the user in the implanted state, the opening in therecessed region will be spaced apart from the skull bone of the user.This allows for feedthrough pins to extend from the feedthrough elementwithout interfering with the skull bone.

An embodiment, the method comprise the further step of electricallyconnecting at least one electric lead to at least one of the metal pinsoutside of the hermetically sealed enclosure and cause the lead toextend in a recessed area from the pin to the outer circumference of theimplantable device. At the outer circumference the leads may be joinedin a spirally coiled multi-wire conductor. Thus leads may pass from thefeedthrough pins to the outer regions of the housing without beingsubject to pressure in case the implanted housing inadvertently ispressed towards the skull bone.

An embodiment of the method comprises the further step of connecting thepins inside the implantable device to a circuit board having a pluralityof interconnected electronic components thereon. This processing stepmay be performed prior to the closing of the hermetically sealedenclosure.

An embodiment of the method comprises the following additional steps:

-   -   place the implantable device in a mould,    -   hold the leads in place in the recessed area,    -   inject hardenable fluid material into the mould in order to form        an overmould which fixates the leads.        Preferably the hardenable fluid is a silicone, which will set        into a flexible but resilient protective substance, which may        absorb mechanical shocks as well as insulate the leads from the        corrosive nature of body fluids.

An embodiment of the method comprises the following additional step:attach in a releasable manner a magnet to an exterior part of theexterior upper cover. Preferably the magnet is provided with a casing,which interfaces with a silicone intermediate part and this intermediatepart ensures a connection with the hermetically sealed housing.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a partial cross section view of an example of acochlear implant housing with an external antenna related to thedisclosure.

FIG. 2A illustrates a partial cross section view of an example of acochlear implant housing according to an embodiment of the disclosure.

FIG. 2B illustrates a bottom view of an example of cochlear implanthousing with a multipolar feedthrough element according to an embodimentof the disclosure.

FIG. 2C illustrates a bottom view of an example of a feedthrough elementwith 4 connection poles in a housing according to an embodiment of thedisclosure.

FIG. 2D illustrates a detailed view of an example of a feedthroughelement with 4 connection poles according to an embodiment of thedisclosure.

FIG. 2E illustrates an example of construction details of a cochlearimplant housing according to an embodiment of the disclosure.

FIG. 3A illustrates a cross section view of an example of a cochlearimplant according to an embodiment of the disclosure.

FIG. 3B illustrates an enlarged portion of the cross section view of anexample of a cochlear implant according to an embodiment of thedisclosure.

FIG. 3C illustrates a cross section view of an example of a cochlearimplant according to an embodiment of the disclosure.

FIG. 3D illustrates a cross sectional view corresponding to FIG. 3B, butnow with the a mold over silicone shealding.

DETAILED DESCRIPTION

Neurostimulation implants can be used to stimulate and/or measureelectrophysiological signals. An example of a neurostimulation implantis a cochlear implant as illustrated in FIG. 1.

The cochlear implant includes an internal portion 100 which issurgically implanted in a patient (e.g., under the skin on the skull)and an external portion 120 which attaches externally above theimplanted portion. In the example of FIG. 1, the cochlear implantincludes an implantable hermetic housing 101 and an external antenna108. The implantable hermetic housing 101 includes electronics 102, areceiving/transmitting antenna 103, and a magnet 104 that holds theexternal portion 120 with the antenna 108 in position. The externalantenna 108 can thus communicate with the electronics 102 in theimplantable hermetic housing. The antennas 103, 108 may be coils,whereby magnetic energy and information may be transferred from the onecoil to the other.

The design of housing 101 is based on a main body 105 made from aceramic, such as alumina, hermetically closed with a flat titanium cover106. The device can be implanted under a user's skin with the main body105 oriented toward the skin (toward the outside of the user) andtitanium cover oriented toward inside of the user. The titanium covercould be adjacent to the skull bone.

The main body 105 includes a plurality of feedthroughs 107 and providesmechanical protection for electronics 102, an air-tight and fluid-tightseal (hermetic seal) and electric insulation of the feedthroughs. Asshown in FIG. 1, a feedthrough includes a pin made of conductivematerial 117 inserted into a small hole 118 formed in the main body 105.The feedthroughs 107 are arranged radially around the outercircumference of main body 105.

FIGS. 2A and 2B illustrate another example of a cochlear implant shownwithout the corresponding external device. In FIG. 2A the right handside is a sectional view, whereas the left hand side is a side-view andin FIG. 2B the section line and side view are indicated. Thus theimplant is shaped as an annular object with a central hole 218 oropening. This central hole 218 serves to receive a magnet 314 as shownin FIG. 3C, which serves the same purpose as the prior art magnet 104.The implant includes a subcutaneous hermetic housing 201, which has aceramic surface 202 on the side which faces the skin of the user, inorder to allow receiving of energy by electromagnetic coupling of a coilof an external device (not shown). The implant also includes a U-shapedmain body 203, made of biocompatible ceramic. The U-shaped main body 203has a U-shaped cross sectional profile, as shown in FIG. 2A. This shapecreates space within the main body to accommodate various componentssuch as electronics board 208. The U-shaped main body 203 can bemanufactured with a Ceramic Injection Molding (CIM) process and offers asolid and strong shape against multiple external constrains such aspressure, impact and shock. According to FIG. 2A, the U-shaped body isannularly shaped to circumvent the central hole 218, wherein the magnet314 is insertable, however the magnet 314 (see FIG. 3C) could well, inan alternative thereto, be placed to circumvent the U-shaped body, inwhich case no central hole would be provided. Also both a centrallyplaced and a circumferential magnetic means could be employed.

FIG. 2B shows a view from the bottom of the cochlear implant, anddisplays the bottom surface of stamped titanium cover 206. The titaniumcover 206 can be manufactured by stamping to obtain the desired shape.

Apart from stamping from a rolled plate item, other ways of processingthe disc like item are possible, such as shaping by machining out of asolid body or by metal powder techniques. A well known powder processingtechniques comprises a first step of pressing a metal powder and abinder into a semi solid body which is later heat treated or sinteredinto a solid metal body of the desired shape. Possibly a final machiningstep is necessary to achieve desired tolerances. A further powdertechnique uses a laser beam which melts titanium power in a layer. Byrepetition of layers, the part is built (like fast prototyping withpolymer). A step of high temperature sintering is needed to obtain thefinal density on the part

As shown in FIG. 2B, the stamped titanium cover 206 includes elevatedparts 210 and an elevated region 211. These elevations 210, 211 areelevated relative to the plane of the cover to abut a common planeindicated by dashed line 228 seen in FIG. 3A, and thus create a recessedregion 220. When the cochlear implant is implanted in a user, betweenskin and bony tissue (such as on the skull of the user), the elevatedparts 210 and elevated region 211 abuts against the bony tissue, whilethere remains a void between the bone tissue and the recessed region220. This void is useful for routing leads of electrodes from remotelocations on the user's body to the implanted device. The leads can thuspass through the recessed region 220 and are protected from shock andimpact by the cochlear implant supported on the elevated parts 210 andelevated region 211. As seen in FIG. 2A connection pins 205 extend outof a plate 225 and into, but not beyond the region between plane 228 andthe recessed region 220.

In an embodiment, elevated parts 210 may be left out of the stampedtitanium cover 206, but instead support on the skull bone may be createdby the addition of a silicone distance mat, which is added on top of therecessed region of the stamped titanium cover 206. In this case thestamped cover 206 would be flat in the entire recessed region withoutelevated parts. The protection of the leads would be created by thesilicone mat being interposed between the leads and the recessed area inthat particular region. Thus, the same functionality may be provided andcreate a secure path for electrodes without actually shaping elevatedparts 210 in the titanium cover.

FIG. 2B illustrates an embodiment with two multipolar feedthroughelements 204. In this embodiment each multipolar feedthrough element 204includes 14 pins 205, whereby each pin forms a connection pole. Thefeedthrough element 204 may comprise a base shaped as a plate 225. Thenumber of pins and the shape of the feedthrough elements are not limitedto the illustrated embodiment.

Each multipolar feedthrough element 204 may be made and the holes 227created with the use of classic processing technique for implantabledevices: a ceramic plate 225 with a first and a second flat side isinitially made and provided with circular holes 227 directly connectingthe first and the second sides, a platinum iridium pin 205 is insertedinto each hole 227, a feedthrough metal welding flange 216B preferablymade from titanium is added to a circumference flange of the ceramicplate 225, and a gold brazing metal is used in a brazing process to fusethe inserted pins 205 and the titanium welding flange 216B to theceramics of the plate 225. By this process an air and fluid tightelectrically insulating plate 225 is provided with a multitude ofelectrical connections from the first to the second side.

By creating feedthrough elements 204 separately from the stampedtitanium cover 206, it is possible to manufacture the titanium cover 206through a stamping process and the multipolar feedthrough elements maybe assembled onto the stamped titanium cover 206 by laser welding due tothe feedthrough titanium welding flange 216B on the feed-through ceramicplate 225. This example of multipolar feedthrough elements 204 has arectangle shape with rounded edges 207 which allows a continuous laserwelding process in the assembly of the ceramic plate and the titaniumcover 206. In this way, feedthrough elements 204 and their connectionsto measuring and/or stimulation electrode leads are protected againstdirect constraints from the environment such as pressure, impact orshock.

Assembly of multipolar feedthrough element 204 may well be achieved by adirect mounting process such as used in surface mounted devices (SMD)where there is already a well laid out and well established process roadfor manufacturing in both large and smaller numbers. In the aboveassembly process steps, it is the process steps up to and including thefusing of the ceramic plate with the pins and metal flange which aremost error prone, however, each feedthrough element comprising ceramicplate 225 with the metal pins 205 and feedthroug welding flange 216B maybe tested prior to installment in the titanium cover 206, andnonfunctional parts, such as parts not being leak proof may bediscarded. This is opposed to the prior art feedthrough generation,where the holes 118 are generated along the circumference of the ceramicmain body 105, and in case one hole with inserted pin 117 comes out notleak proof, the entire main body has to be discarded, as an individualpin 117 is not exchangeable. This is at a time where a lot of processinghours and expensive material has been incorporated into the main body,and the result is poor yield.

FIG. 2A illustrates some internal components including electronics board208. Electronics board 208 is mounted by the pins 205 that enter intoholes of electronics board 208 before they are soldered to gain contactwith the circuitry embedded in the electronic board. These pins 205 passalso through the sealed holes 227 of the feedthrough elements 204. FIG.2E provides additional detail through an enlarged view of a crosssection of the cochlear implant.

FIG. 2E illustrates an example of the construction of the implantablehermetic housing 201. Inner and outer titanium welding flanges 216A maybe placed between the U-shaped main body 203 and the stamped titaniumcover 206. A titanium feedtrhough welding flange 216B may be placedbetween the feedthrough element 204 and the stamped titanium cover 206.The components may initially be brazed at brazing locations 217 in anoven to fuse the welding flanges 216A, 216B to the ceramic plate 225 andmain body 203 respectively. The laser weld process finalizes thehermetically sealed hosing 201. A laser weld 211 runs along the entirecircumference of the main body 203 and has a weld intersection parallelto the common plane 228. A laser weld 212 runs along the innercircumference of the main body 203 and has a weld intersection which isperpendicular to the common plane 228, and lesser welds 215 runs alongthe perimeter of each ceramic plate 225 of every feedthrough element andalso here the weld intersection is perpendicular to the common plane228. The advantages of the laser welds are that they are leak tightseams which may be generated without any production of fumes or gasses,and at the same time heat dissipation to brazed areas nearby or to theelectronic components inside the housing 201 is manageable due to theshort heating time and very limited metal melt zone. The laser weldingmay be performed in a controlled atmosphere to ensure that theatmosphere inside the housing 201, which will be sealed off in anairtight manner by the welding process, has well known and pre-definedproperties. Preferably the gas inside the hermetic chamber is a mix ofargon and helium. The argon part provides for a protective atmosphere,where as the helium gas allows for leakage test.

FIGS. 2C and 2D illustrate an example of a multipolar feedthroughelement that is a quad polar feedthrough element 209 having four pins205. The round shape of feedthrough element 209 facilitates laserwelding of the feedthrough element to the stamped titanium cover 206.

An implantable connector (not shown) could be connected to thefeedthrough pins 205 in order to connect leads for neuromodulationelectrodes, cochlear electrode array, measuring electrodes for ECAPmeasures, an electromechanical actuator or antennas among others.

FIGS. 3A-C illustrates an example of additional details of componentswithin the implantable hermetic housing 201. As shown in FIG. 3A, avoluminous area of the housing is formed between the inside of theU-shaped body 203 and the inside surface of the elevated region 211 ofthe stamped titanium cover 206. Arrow 307 shows the height of this area,and as seen in FIG. 3A this height allows integration of components onboth sides of board 208, namely on the ceramic side 308 and on the lidside 309.

A tight area indicated by arrow 311 is defined between the ceramic plate225 and the inside surface of the U-shaped body 203. In this area,components can be integrated only on the ceramic side 308 as the lidside 309 is reserved for the feedthrough element.

The ceramic side 308 may house an antenna 310 in order to be closest tothe skin and the corresponding external antenna. The antenna 310 may bea coil. The lid side 309 can house the thickest components such assignal processors as it has the largest sectional depth 307. The coil310 couples wirelessly with a coil provided externally of the implantedhousing, and energy as well as information is transmitted, through themagnetic coupling of the two coils, from the external part to theinternal part, and an information signal may pass from the coil 310 ofthe implanted part to the external antenna. Possibly the implanteddevice comprises a rechargeable battery to facilitate the transmissionof a wireless signal from the implanted part to an external receiverantenna and also to supplement the energy consumed by the electrodes intimes of high demand.

Alternatively or as a supplement to the antenna 310, energy harvestingby movement may be implemented as known from mechanical wrist watches: ahalf-circle shaped disk rotates around its centre, caused by theunbalance and the movements of the watch by the arm. This rotation windsthe clock spring. Such a system may be added into the implanted device,together with the housing. Here the rotation from the half-disk is usedto drive a small generator, designed to produce power and able to chargea small rechargeable battery—designed to supply the cochlear implant.The energy harvester could be designed in many ways: another example isa magnet in a tube with a coil around it, able to move back and forthaccording to the movement of the head. This principle is known from thebattery-free so-called shake flashlights. To facilitate the smaller sizeof the implant, the rotating system may be placed in a separate cabinet,implanted elsewhere in the head and connected to the cochlear implantthrough a wire. If the implant is placed right under the skin, a solarcell in the unit could add energy for charging during the day. However,the skilled person would appreciate that the energy harvester may alsobe placed at a different location in-vivo.

As shown in FIG. 3B, the recessed region 220 forms a space between thestamped titanium cover 206 and the skull bone tissue 302. The wires orleads 303 which connect the pins in the feed-through to a deviceexternal to the housing 201, such as to electrodes, sensors, antennas ortransducers pass in this space wherein they are protected against shockand impact by a silicone overmolding 304 as seen in FIG. 3C and by theelevated parts and regions.

As seen better in FIG. 3C, the leads 303 pass out from the region of thehousing and form a spiral 305 which is able to absorb forces that couldbe applied to the lead 303. The spiral 305 is able to be stretched,folded and bend and can thus adapt to the individual surgery and theshape of the mastoidectomy as well as adapt to cranial growth and otherchanges which may take place after surgical implant of the device. Thespiraled coil is wound around a pin, which is then drawn out to leave avoid 310 at the center of the spiraled coil. Along the spiral, placedinside the void 310 left by the pin, or outside it such as along theground electrode an antenna lead for FM communication may be placed.Also possibly any of the ground electrode, a measuring electrode, astimulation electrode, or a lead passing over the top of the head to animplant at an opposed side of the head, may be used additionally as aradio antenna. Any inside or outside surface of the implanted housing orthe circuitry board 208 may serve as a carrier for a radio frequencyantenna such as a patch antenna or a rod antenna. Such antennas couldallow the implanted part to communicate with external units by Bluetoothor similarly coded protocols, which could provide a wider band-width ofthe communication between external part and implanted part, than what isobtainable by means of the coil 310. This requires an additional radioto be incorporated into the internal part. The higher frequencies usedin usual RF transmission of information lead to a high degree ofattenuation when transmitted through human tissue, however, the externalantenna part and the implanted part are placed in very close proximityand are also located in well known positions with respect to each other,which allows for antenna designs with a high degree of directionality tobe used, and also their closeness to each other situates the externaland internal antennas within the near field of each other, and these twofact may ensure very good coupling between such two antennas, and thismay overcome the problems of attenuation of the RF frequency signalstransmitted through the tissues of the user. A similar argument goes forRF frequency transmission of signals between two implanted devicesplaced at each side of the head, whether the signals are transmitteddirectly from implanted part to implanted part, or signals are exchangedfrom one external part to the other, or from one external part to bothof two implanted parts being placed at each side of the head of a user.One particular frequency band which would be open to such communicationRF signals would be the band around 2.4 G Hz used for Bluetooth andBluetooth low energy transmission. A patch antenna with a directionalcharacteristic is disclosed in WO2007019855 and such an antenna could beused.

The potential mix-up of the two BTE and antenna parts for the respectiveleft and right ear can cause problems for users with an implant at eachear, because of differences in the two implants and/or stimulationschemes for the left and right ears. Also in school classes with manypupils carrying similar implant and external parts, such a mix-up maytake place between pupils. An ID-chip, such as an RFID chip in eachimplanted part for identification is available and need only tocommunicate a short distance to the BTE (Behind The Ear) part or to theantenna part and to such a purpose only limited power and a smallantenna is needed. A simple hand-shake procedure between external partand implant may be instigated prior to on-set of transmission of soundsignals, to ensure that it is the correct external part, and not a partbelonging to the other ear or a school friend. The identification handshake may take place by means of the coil antennas in the external andinternal parts, however here the communication is not so fast. InUS2005/0255843A such an identification scheme is disclosed, which allowsproprietary communication using magnetically coupled coils between twoseparate devices, such as a first and a second hearing aid sitting oneach one of a users ears. This technique could also be implemented andused between an implanted part and an external part, provided theinternal part has some energy storage capacity, eg a battery, whichwould allow it to transmit its own identification code to the externalpart when prompted.

FIG. 3D shows how the overmold with a hardenable substance such assilicone encapsulates the housing 201. The silicone fills the void madeunder the housing by the recesses and elevated parts of the titaniumcover 206 whereby all leads in the area are fixated and protected bothagainst shock and tissue fluids of the body. Also al the pins of eachfeed-through are completely embedded in the silicone and therebyprotected.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims.

LIST OF ELEMENTS

-   100 internal portion-   101 implantable hermetic housing-   102 electronics-   103 receiving antenna-   104 magnet-   105 main body from ceramic-   106 flat titanium cover-   107 feedthrough-   108 external antenna-   117 conductive material pin-   118 small hole-   120 external portion-   201 subcutaneous hermetic housing-   202 ceramic surface-   203 u-shaped main body-   204 multipolar feedthroughs-   205 pin(s)-   206 stamped titanium cover-   207 rounded edge-   208 electronics board-   209 quad polar feedthrough-   210 elevated part-   211 elevated region-   212 outer laser weld-   213 inner laser weld-   215 feed through laser welds-   216A upper cover titanium welding flange-   216B feedthrough titanium welding flange-   217 brazing locations-   218 central hole-   220 recessed region-   225 ceramic plate-   227 hole-   228 common plane-   302 skull-   303 wires-   304 silicone overmolding-   305 spiral-   306 lead-   307 voluminous area arrow-   308 ceramic side-   309 lid side-   310 antenna-   311 tight area arrow-   314 exchangeable magnet

The invention claimed is:
 1. A device configured to be implantable underskin, comprising: a sealed housing containing electronics for at leaststimulation or collection of data and at least one antenna forcommunicating with an external device; a magnet configured to hold saidexternal device in proximity to the sealed housing, wherein the sealedhousing includes an upper cover configured to be closest to the skinwhen the device is implanted, and a lower cover that is hermeticallyconnected to the upper cover, the lower cover includes an elevatedregion and an elevated part, a recessed region, and at least onefeedthrough element formed in the recessed region of the lower cover,wherein the elevated part and the elevated region are elevated relativeto a plane of the lower cover defined by the recessed region, such thatthe elevated part and the elevated region are configured to abut againsta bone tissue thereby creating a void between the device and the bonetissue at the recessed region, the lower cover has a circular disc outerperimeter shape, the at least one feedthrough element, the elevatedregion, and the elevated part are positioned along a diametrical linesuch that the at least one feedthrough element and the elevated part areon one side of a central hole of the lower cover, with the elevated partbeing positioned farther away from the central hole than the at leastone feedthrough element, and the elevated region is on the opposite sideof the central hole than the at least one feedthrough element and theelevated part.
 2. The device according to claim 1, wherein the at leastone feedthrough is prevented from extending beyond the elevated region.3. A device configured to be implantable under skin, comprising: asealed housing containing electronics for at least stimulation orcollection of data and at least one antenna for communicating with anexternal device; a magnet configured to hold said external device inproximity to the sealed housing, wherein the sealed housing includes anupper cover configured to be closest to the skin when the device isimplanted, and a lower cover that is hermetically connected to the uppercover, the lower cover includes an elevated region and an elevated part,a recessed region, and at least one feedthrough element formed in therecessed region of the lower cover, wherein the elevated part and theelevated region are elevated relative to a plane of the lower coverdefined by the recessed region, such that the elevated part and theelevated region are configured to abut against a bone tissue therebycreating a void between the device and the bone tissue at the recessedregion, and the device further comprises a U-shaped body, the U-shapedbody and an inside surface of the elevated region forming a voluminousarea therebetween into which at least one component of the device isintegrated.
 4. The device according to claim 1, wherein the devicefurther includes a U-shaped body, and an inside surface of the U-shapedbody and a ceramic plate defines a tight volumetric area.
 5. The deviceaccording to claim 4, wherein the ceramic plate comprises a ceramic sideconfigured for integrating components within the tight volumetric area.6. The device according to claim 1, wherein the at least one feedthroughelement includes a plate shaped base with one or more holes, and the atleast one feedthrough element is configured to connect an electrode tothe electronics housed within the sealed housing through conductive pinsin the one or more holes.
 7. The device according to claim 6, whereinthe plate shaped base of the at least one feedthrough element ishermetically joined to the lower cover of the external housing.
 8. Thedevice according to claim 1, wherein the elevated part is locatedradially adjacent to the at least one feedthrough element.
 9. The deviceaccording to claim 1, wherein the lower cover is made of titanium. 10.The device according to claim 1, wherein the sealed housing is acochlear implant configured to be implanted under the skin of a humanuser and above the user's skull bone.
 11. A cochlear implant apparatuscomprising the implantable device according to claim 1 and an externaldevice.
 12. The device according to claim 1, wherein the device isshaped as an annular object with a central hole or opening, the centralhole or opening being configured to receive the magnet.
 13. The deviceaccording to claim 1, wherein the upper cover has a hollow crown made ofa biocompatible material and permeable to electromagnetic wavesincluding magnetic fields.
 14. The device according to claim 13, whereinthe hollow crown includes an external wall forming an external radialperiphery of the sealed housing, and an internal wall oriented towards acenter of said sealed housing, the external wall and the internal wallform an opening of an annular U-shaped groove, and the internal wall ofthe hollow crown further forms the central hole or opening that isconfigured to receive the magnet.
 15. The device according to claim 13,wherein the biocompatible material is aluminum oxide.
 16. A deviceconfigured to be implantable under skin, comprising: a sealed housingcontaining electronics for at least stimulation or collection of dataand at least one antenna for communicating with an external device; amagnet configured to hold said external device in proximity to thesealed housing, wherein the sealed housing includes an upper coverconfigured to be closest to the skin when the device is implanted, and alower cover that is hermetically connected to the upper cover, the lowercover includes an elevated region, a recessed region, and at least onefeedthrough element formed in the recessed region of the lower cover,wherein the device is shaped as an annular object with a central hole oropening, the central hole or opening being configured to receive themagnet, the upper cover has a hollow crown made of a biocompatiblematerial and permeable to electromagnetic waves including magneticfields, the hollow crown includes an external wall forming an externalradial periphery of the sealed housing and further includes an internalwall oriented towards a center of said sealed housing, the external walland the internal wall of the hollow crown form an opening of an annularU-shaped groove, the internal wall of the hollow crown further forms thecentral hole or opening that is configured to receive the magnet, theelevated region of the lower cover has a crescent shape spanning morethan 50% of the lower cover, and the at least one feedthrough element issurrounded on two sides by ends of the crescent shape.
 17. The deviceaccording to claim 16, comprising: two feedthroughs, each feedthrough ofsaid two feedthroughs having a rectangular shape with rounded cornersand having 14 connector pins.
 18. The device according to claim 17,comprising: two feedthrough elements, each feedthrough element of saidtwo feedthrough elements having a circular shape and having 4 connectorpins.
 19. The device according to 16, further comprising: anelectrically conducting lead connected to the at least one connector pinof the feedthrough element, and thereby electrically connected to theelectronics in the sealed housing; a silicone overmoulding surroundingthe conducting lead, wherein the lead passes through a recessed region,to reach an outer circumference of the lower cover.